The FreeBSD folks run tests on positive and negative leap seconds to make sure things are fine: * https://lists.freebsd.org/pipermail/freebsd-stable/2020-Novem

The FreeBSD folks run tests on positive and negative leap seconds to make sure things are fine: * https://lists.freebsd.org/pipermail/freebsd-stable/2020-November/092837.html https://lists.freebsd.org/pipermail/freebsd-stable/2020-Nove... Of course there's a whole lot of other userland code besides ntpd.